PostgreSQL: Treat infinite values in date like datetime consistently

The values infinity and -infinity are supported by both date and
timestamp types.

https://www.postgresql.org/docs/current/static/datatype-datetime.html#DATATYPE-DATETIME-SPECIAL-TABLE

And also, it can not be known whether a value is infinity correctly
unless cast a value.

I've added `QueryAttribute#infinity?` to handle that case.

Closes #27585.

1 files changed, 24 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/date_test.rb b/activerecord/test/cases/adapters/postgresql/date_test.rb
new file mode 100644
index 0000000000..1562acdcc3
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/date_test.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "models/topic"
+
+class PostgresqlDateTest < ActiveRecord::PostgreSQLTestCase
+  def test_load_infinity_and_beyond
+    topic = Topic.find_by_sql("SELECT 'infinity'::date AS last_read").first
+    assert topic.last_read.infinite?, "timestamp should be infinite"
+    assert_operator topic.last_read, :>, 0
+
+    topic = Topic.find_by_sql("SELECT '-infinity'::date AS last_read").first
+    assert topic.last_read.infinite?, "timestamp should be infinite"
+    assert_operator topic.last_read, :<, 0
+  end
+
+  def test_save_infinity_and_beyond
+    topic = Topic.create!(last_read: 1.0 / 0.0)
+    assert_equal(1.0 / 0.0, topic.last_read)
+
+    topic = Topic.create!(last_read: -1.0 / 0.0)
+    assert_equal(-1.0 / 0.0, topic.last_read)
+  end
+end